Bearing and mechanical seal support systems or other support systems for turbomachinery often may use fluid flow systems, which use various system devices to control the flow of a fluid, such as a gas or liquid through the support systems. The fluid flows through an operational system device but is switchable by a transflow valve to a standby system device. The fluid flow systems include a variety of fluid handling or transfer valves, which define independent fluid flow lines having flow passages through which flow is directed, controlled and in many cases diverted from one independent flow line to another fluid flow line. These fluid flow systems can include a variety of system components and devices that are used in a variety of different applications. For example, such system devices may include process filters, seal gas filters, fuel gas filters, lube oil filters, seal oil systems, scrubbers, gas-liquid separators, heat exchangers (cooling or heating) and gas or oil heaters used in any industry application. Accordingly, such devices are used with the bearing or mechanical seal support systems for turbomachinery where continuous and uninterrupted supply of a gas or liquid is needed for the main equipment and system.
In such applications, it is desirable for continuous fluid flow through the system, such that when one system device is spent or requires maintenance, another standby device can be brought on-line immediately so that the entire system need not be shut down. In one example, a fluid delivery system used for pumps, compressors or other types of rotating equipment for fluid delivery will include mechanical seals on the rotating equipment to seal such equipment, which seals are supplied with dry gas such as a barrier or buffer fluid in a conventional manner. It is necessary to continuously supply such gas during operation of the rotating equipment, wherein such gas will pass through the system devices, such as seal gas filters, that are provided in the gas supply system.
Thus, multiple or redundant system devices, such as gas seal filters, may be placed adjacent to one another, with at least one of the system devices being shutoff from the system, i.e. on standby, while at least one other system device is being used, i.e. is operational. Such a set-up allows a user or automated system to select which of the system devices are to be used at a certain time as the operational device and which devices are not to be used so as to serve as the standby device. Once an operational system device is spent or requires servicing, the operational device is shutoff from the system for replacement or maintenance and the standby device is put on line in its place.
To affect shutoff or switching between fluid treatment devices, transflow valves are used to isolate and switchover the system devices so that fluid flow switches from the operational device to the standby device.
Conventional transflow valves can be constructed using three way ball valves such as that shown in FIG. 1 which are provided with one common spindle to operate the flow through the inlet and outlet sections of the transflow valves together in unison. Generally, there are two types of transflow valves used in industry, wherein one is a single block and bleed (SBB) valve (FIG. 1) and another one is a double block and bleed (DBB) valve (FIG. 2). The SBB transflow valve of FIG. 1 has one common spindle CS-1 connected to valve stems of an inlet transflow valve V1-1 and an outlet transflow valve V2-1. The DBB transflow valve of FIG. 2 has three valve spindles CS1, CS2, and CS3 linked together by a common handle assembly HL-2 to operate six transflow valves through one single operation.
More particularly, FIG. 1 is a schematic of a single block and bleed (SBB) transflow valve currently used in industry. In this drawing, A represents the equipment in operation, i.e. the operational device, and B represents the equipment in standby mode, i.e. the standby device. Each device has a vent and drain and is supplied by a respective inlet and outlet which are controlled through the valves V1-1 and V2-1, which in turn are connected to the main INLET or OUTLET. The valves V1-1 and V2-1 have respective valve stems connected to the common spindle CS-1 which is rotated manually by the handle HL-1.
The inlet and outlet for device A respectively have bleed valves B1-1 and B2-1 connected thereto, while the inlet and outlet for device B have respective bleed valves B3-1 and B4-1 connected thereto. A pressure equalizing valve E is also provided. Rotation of the spindle CS-1 by the handle HL-1 simultaneously switches the inlet and outlet transflow valves V1-1 and V2-1 between devices A and B. Hence, a fluid supply connected to device A is isolated from device B based on the valve position for valves V1-1 and V2-1, but the fluid supply can be switched over to device B and shut off from device A without affecting the flow to the devices downstream of the SBB transflow valve. Using valves V1-1 and V2-2 by operating the common spindle (CS-1) and the handle (HL-1), the device A is in operation and device B is in standby mode. Device B can be attended to for maintenance such as changing of the filter elements if the devices A and B were gas seal filters. Prior to the maintenance, the stand by side bleed valves B3-1 and B4-1 are normally closed but then opened to depressurize the device vessel 2 for safety prior to maintenance. By operating the valve position, the flow can be changed to switchover the flow to device B while device A becomes the standby device.
In the DBB transflow valve of FIG. 2, this also is a known device used in industry. Here again, A represents the equipment in operation and B represents the equipment in standby mode. This valve configuration uses a first block valve comprising inlet and outlet transflow valves V1-2 and V2-2, and a second block valve comprising inlet valves V3-2, V4-2 and outlet valves V5-2 and V6-2. These valves are connected in pairs by common spindles CS1, CS2 and CS3 which are all connected by handle linkage LK-2 operated by handle HL-2. Manual rotation of the handle HL-2 rotates the common spindles CS1, CS2 and CS3 through linkage LK-2 which in turn opens and closes the appropriate transflow valves. In this regard, the fluid supply may be connected to device A and isolated from device B based on the valve position for interconnected valve pairs V1-2/V2-2, V3-2/V5-2, and V4-2/V6-2. The fluid supply can be switched over to device B without affecting the flow to the devices downstream of the transflow valve assembly.
Therefore, main inlet and outlet valves V1-2 and V2-2 of the first block valve define the main switchover valve for diverting the fluid flow direction towards devices A or B, while the inlet and outlet valves V3-2 and V5-2 define the second block valve for device A and inlet and outlet valves V4-2 and V6-2 define the second block valve for device B. By operating the handle HL-2, all of these six valves are operated simultaneously. Notably, valves B1-2, B2-2, B3-2, B4-2, B5-2, B6-2, B7-2 and B8-2 are bleed valves, which are normally closed and selectively opened to depressurize the devices A or B during maintenance.
In another commercial design of a transflow valve for a double block and bleed (DBB) application (FIG. 3), this design is based on using a SBB design for first block valves (V1-3 and V2-3), which are connected by a common spindle CS and operated by a handle HL like in FIG. 1. This design uses separate second block valves (V3-3, V4-3, V5-3 and V6-3), which are independent valves operated by their own respective handle H3, H4, H5 and H6. B1-3, B2-3, B3-3, B4-3, B5-3, B6-3, B7-3 and B8-3 are bleed valves, which are normally closed and selectively opened to depressurize devices A or B during maintenance.
In operation, if any one of these transflow valves (V3-3, V4-3, V5-3 and V6-3) are operated incorrectly by being closed when it should be open, the process device A or B will lose the supply of fluid or may allow the fluid flow to flow in the wrong direction and cause an operational issue and unsafe maintenance. This arrangement depends on the skill set of the operator and a thorough understanding of the valves positions by the operators. Hence, this design is not a fool proof device and depends on the operator's skill and care.
It is an object of the invention to provide an improved transflow valve assembly, which overcomes disadvantages associated with known transflow valve designs.
The invention relates to an improved double block and bleed transflow valve which uses one single spindle interconnecting the inlet and outlet transflow valves with which valves also drive a gear train mechanism connecting all six valve stems. As such, by operating one main spindle connected to the two inlet and outlet transflow valves, all six valves of this double block and bleed configuration operate simultaneously through the common spindle and gear train mechanism and assure an uninterrupted flow of fluid from one device to another standby device.
Generally, the preferred design of the present invention includes two system devices and in particular, two fluid treatment devices such as gas seal filters, where inlet and outlet flow to and from the filters is controlled by respective inlet and outlet transfer valves, which selectively switch or transfer fluid flow from one filter to another. These system devices may be any type of such devices used with transflow valves, and it will be understood that the fluid transfer valves disclosed herein are usable with various types of turbomachinery devices which receive and transfer fluid that flows therethrough. For example, the inventive fluid transfer valves can be provided on the upstream and downstream sides of one or more fluid handling or flow devices to selectively switch or transfer flow of fluid from one device to the other.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “up”, “down”, “right” and left” will designate directions in the drawings to which reference is made. The words “in” and “out” will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. The words “proximal” and “distal” will refer to the orientation of an element with respect to the device. Such terminology will include derivatives and words of similar import.